In various practices it is desirable to remove ingredients such as organic contaminants or inorganic ions which may be present as contaminants from a fluid (gas or liquid). For example, filters are used in laboratories and elsewhere for collecting contaminants from fluids such as water in order to purify the fluid and/or to analyze the contaminants. It is known to provide adsorbent material such as coated silica in order to remove the ingredients from the fluid. One practice involves the use of an extraction disk marketed by 3M under the trademark Empore.RTM. . Such disks are available in various membrane formats. One of these formats is the standard density format which is advertised as being able to process a wide range of sample types and volumes. The disk contains standard (55 micron) particle size sorbents. Another membrane format is high density which contains small (12 micron) particle size sorbents and is advertised as processing cleaner sample matrices in limited volume. Both forms of membrane formulations are intended to entrap sorbent particles within an inert matrix of polytetrafluoroethylene. The resulting particle-membrane (90% particles:10% PTFE, by weight) is said to result in a denser more uniform extraction bed than is achieved from SPE (Solid Phase Extraction) cartridges made from loosely packed particles. These disks use various particle types, such as silica, resins and ceramics. One form of Empore.RTM. incorporates a Teflon.RTM. web to entrap irregular shaped particles. The Telfon.RTM. web density and fibril diameter varies throughout the structure. The particles are generally of a size of 10-20 micron and Teflon fibrils comprise about 1/2 of the volume. Some specific uses of the disks are for oil and grease extraction. For example, an Oil & Grease Disk was intended for a Proposed EPA Method 1664 (N-Hexane Extractable Materials and Silica Gel Treated N-Hexane Extractable Material by Extraction and Gravimetry). The Empore.RTM. Oil & Grease disk is a multilayer structure which incorporates a center sorbent layer. Teflon fibrils create loose webbing throughout so as to trap spherical-shaped particles. The open web structure leaves space between the particles and also leaves gaps in the overall structure. Some irregular particles fill in between large spheres. The particle size is 60 micron spheres and 10-12 micron for the irregular particles. The Teflon fibrils comprise about 1/2 of the volume.
Another known form is the Restek Resprep.TM. C18AR 47MM Disk which is a single layer having a dense center with loose particles on the top and bottom to result in a very porous structure. Small spheres (5-12 micron) are located throughout with large open areas throughout. Glass material fills 50% or more of the surface area. The center has larger clumps of material with spherical media filling in portions of the surrounding area. The sorbents do not form a dense bed or continuous layer. There is a very open but continuous version of sorbent spheres in the glass.
In other titration practices, it is desirable to disperse ingredients into a fluid. Known uses for adding ingredients include the use of filter type structures which contain additive materials for beverages such as powdered cream or sugar in pockets. The liquid dissolves the material while passing through the pockets. Such uses are described, for example, in U.S. Pat. Nos. 5,567,461 and 5,885,633.